Punch machine programmed directly by electromagnets



J- RABINOW May 11, 1965 PUNCH MACHINE PROGRAMMED DIRECTLY BY ELECTROMAGNETS 2 Sheets-Sheet 1 Filed Oct. 7, 1963 T Fig. la

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c005 cam 4M0 Jacob Rab/now J. RABINOW May 11, 1965 PUNCH MACHINE PROGRAMMED DIRECTLY BY ELECTROMAGNETS Filed Oct. 7, 1963 2 Sheets-Sheet 2 Fig. 3

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United States Patent PUNCH MACHINE PROGRAMMED DIRECTLY BY ELECTROMAGNETS Jacob Rabinow, Bethesda, Md., assignor, by mesne assignments, to Control Data Corporation, Minneapolis, Minn., a corporation of Minnesota Filed Oct. 7, 1963, Ser. No. 314,267 14 Claims. (Cl. 234-108) This invention relates to tape or card punch machines, and particularly to improvements therein leading to simplicity, compactness, and increased speed.

Most modern punch machines have a punch and die set, a plurality of interposers for the punches of the set, together with means to cause relative motion between the punches and die after the machine has been programmed (by actuating selected interposers) for a perforation cycle. Substantially all commercially available machines use electromagnets to actuate selected interposers for programming the punch machine between perforation cycles.

There are many design variations in interposer systerns for punch machines. A selected few are disclosed in US. Patents Nos. 3,081,030 and 3,059,844 and 3,011,- 697 and 2,970,753 and 2,732,900. Although various interposer mechanisms dilTer quite drastically, the basic accomplishment is the same. Electromagnets are used to operate one or more mechanical members in a manner such that they interpose selected punches just prior to the punch operation. It has undoubtedly occurred to many designers that material advantages, e.g., simplicity, speed, noise reduction, etc. could be obtained if the punch elements were directly actuated by electromagnets. The electromagnets are required because they are selectively actuated in response to input signals to punch codes into the tape or card. But mechanical interposers used with the electromagnets are a tolerated necessity to overcome a serious power deficiency in conventional electromagnetic actuators. In conventional machines the comparatively small forces of electromagnets are used to actuate an easily moved mechanical part (to interpose the punch elements), after which a considerably more powerful driver is used for driving the interposed punch elements through the card or tape. In general, the small size and high power requirements of an electromagnet to directly actuate a punch element in a punch machine are too severe, particularly in gang punches where many punch elements must be crowded into a small space. Even if the power requirement and space problem were overcome, direct-acting electromagnets used in the ordinary and expected way could not achieve reasonably high speeds because their armatures would have to be quite heavy and the inertia and momentum would seriously limit maximum speeds.

An object of my invention is to provide a punch machine using direct-acting electromagnets in a manner such that no mechanical interposers are required.

In my punch I can use substantially any punch and die set, together with conventional means for causing relative motion between the die and the set of punches to perforate the record at preselected punch positions. Where prior punch machines use solenoid-actuated mechanical interposers to preselect the punch positions for perforation, I use conventional electromagnets of the variable gap type to push forward and hold preselected punches, i.e. those which should perforate the record. Thus, those punches which are to perforate the record in a given punch-operation are directly electromagnetically held in a forward position with respect to the remaining punches of the set.

Summarizing, many designers have attempted to use the force of an electromagnet directly to drive a punch element through a tape or a card in forming a record. There are some very great problems in this connection which my invention overcomes.

A brief review of the method of operation of an electromagnet is in order here, but if one wishes, one can get a complete and detailed analysis in the book entitled Electromagnetic Devices by Herbert C. Roters published by John Wylie. A standard D.C. electromagnet has, generally speaking, a variable gap and if one plots the pull of the armature against the distance travelled, one finds it has a very sharply rising curve just as the armature bottoms, that is, as the gap closes down to zero. This comes about because the flux rises and the pull is proportional to the square of the flux, other things being equal. In order to make the pull a constant, various expedients are resorted to, the most common being the tapering of the core of the armature in such a way that the flux does not rise appreciably as the armature moves in toward the fixed part of the electromagnet. Unfortunately, doing this decreases the pull greatly so that while the sharp rise is minimized, the pull is also reduced, particularly at the very end of the stroke (see Roters). Now, it is entirely possible to build the electromagnets large enough, with enough force, to punch a paper tape or a card, but this is very expensive and requires very large magnets and results in magnets which are very slow.

Let us examine some of the detailed problems. A punched card is approximately .007 inch thick. The space between the die plate and the stripper has to be large enough to easily accept the passage of such a card, so that it is of the order of .010 to .012 inch. The punch travel has to be at least equal to this distance to perforate the card and, in fact, has to be considerably larger because of the usual tolerances of the mechanism, so the stroke due to the paper thickness and the gap itself would be of the order of at least .015 inch. However, since the punches and their moving devices have play and since they have to be periodically sharpened, they are usually made somewhat longer than necessary so that in practical machines, a stroke of .032 to .062 inch is quite common. This means that if an electromagnet is used directly to actuate the punch, it should have a stroke of at least inch and this means a very large number of ampere turns would be required to drive the punch. The force on the punch must be of the order of ten pounds to pierce a hole through one or two layers of paper or card stock. As the punches get dull, this force may exceed these figures.

Another problem that arises in connection with electromagnets operating punches directly, is that the electromagnets are quite large, of the order of two inches square in their mounting area. Because the paper punches have to be close together, as many as one hundred to a square inch, rather elaborate linkages are required between the electromagnets and the punches. One such linkage which is quite straightforward and simple is a Bowden wire, which is a push or pull wire enclosed in a tube or a spiral wire spring which, in turn, is held by a suitable framework so that the wire can transmit forces around a gradual bend. Such Bowden wires, then, can connect a group of punches to a group of electromagnets which are spread out in any suitable array. In order to make the Bowden wires move through their mounting easily, particularly when they are thick and stiff I prefer to use a Bowden wire in the shape of a segment of a circle, that is in a simple are. In this way, the wire does not have to do any bending as it moves through its sheath. This implies, of course, that the electromagnets have to be arranged in a somewhat spherical pattern at some distance from the punch plate. Now, if the magnets were to drive the punches directly by means of such Bowden wires, the wires would be under heavy stress during the punching cycle and would rub against their housings. This would produce a large frictional force opposing the motion of the wires, which means that the electromagnets would have to be made still larger to overcome this force. There would, also, be the attendant wear and more frequent adjustment due to this wear.

I overcome the above mentioned disadvantages of size, friction and the requirements for large currents by using smaller magnets which actuate the Bowden wires and push the punches forward into their punching position but which do not execute the perforation of paper during this action. The electromagnets have to be merely strong enough to hold the punches forward while the punching itself is done by an oscillating die plate driven by a suitable mechanical means. This can be an eccentric, a set of cams, or the equivalent. The forces that can be obtained in this way are very large because the mechanical energy that can be supplied to a die set can be of any desired magnitude at very little expense. Only one such mechanism is needed, regardless of how many holes are punched. In other words, an entire card can be punched at once with its approximately one thousand holes, and a suitable flywheel can provide the necessary force for the punching. Another great advantage of moving the punches into posi tion while they are not actually exerting the force on the paper is that during such motion they are not loaded and the wear on the housings and the mechanism, in general, is very slight. They remain still during the high-force cycle, and there is no wear owing to sliding friction. T-he retracting of the punches can be done in one of many ways, and these will be described later.

The electromagnet design for my punch is very simple and straightforward. I do not need and, in fact, do not wish to have a constant force during the stroke of the electromagnet. I need the maximum pull when the air gap is zero. This is probably best done by having fiat surfaces of the electromagnet as shown in my drawings. When the gap is closed, the exciting current can be very small, and the fact that with such small currents the pull when the gap is opened is also small, is not a problem since all the force I need with the gap open is just enough to move the electromagnets into position. For programming the punch machine I can start moving the punch elements as soon as the paper starts retracting from its punch position. This means that I have roughly half the cycle time to move the punches into position. Residual magnetism which is a bugaboo for many machines is not a serious problem with my machine because if a particular punch element remains in position due to residual magnetism, a benefit is gained if that punch is called upon for a punch operation in the next cycle of the machine. This will be described in detail later.

One of the main advantages of using a small electromagnet with a small gap and a small number of ampere turns is that the speed of the device is greatly increased since the speed of an electromagnet is generally speaking, proportional to the energy that has to be stored in it. In other words, the smaller the number of ampere turns and the smaller the electromagnet, the less energy one has to feed into it to build up the field and to dissipate when the field is collapsed. Both of these effects greatly help to increase the speed of the electromagnet. The other advantages of small size, low cost and simple design are, of course, also important.

When I speak of zero gap, I do not mean that the gap in fact has to be exactly zero. In practice, even an iron-to-iron gap does have some reluctance because of the imperfect mating of the surfaces, and it is sometimes advantageous to have a small fixed gap in an electromagnet, particularly if the iron has a great deal of residual so as to prevent the magnet from having too high a residual magnetic force. This is particularly important in those designs where it is desired that the punches return to their non-punching position after every stroke. These fixed gaps, in the design of my electromagnet will be made extremely small, if used at all.

To summarize then, I use an electromagnet to move the punch element forward into its punching position and to hold it there when the paper is driven against it by the die plate. During the high-force stroke, the magnet is in a static condition and has to provide enough force to hold the punch against the action of the paper and the die. The magnet does not have to provide the force for the length of the stroke, so the total energy supplied by the magnet as far as punching is concerned is theoretically zero. The energy is supplied, of course, by the mechanical reciprocating device that moves the die plate.

Another object of my invention therefore is to provide a punch machine using a conventional punch and die set, which has electromagnets to hold their punches fixed during a punch cycle by the maximum available electromagnetic force of the electromagnets.

Another object of my invention is to provide a punch machine as above, wherein the electromagnets each have an armature and a pole piece between which there is a variable air gap. My arrangement is such that the gap is at a minimum at the time of record perforation. Thus, the maximum available electromagnetic force of the magnet is used to hold the punch element at the time that other means are used to cause the punch to perforate the tape or card.

Other objects and features will become apparent in following the illustrated form of my punch machine which is given by way of example of my invention.

FIGURE 1 is a fragmentary sectional schematic view showing my machine during a record-perforation cycle.

FIGURE 1a is a view similar to FIGURE 1, but just prior to perforation.

FIGURE 2 is a fragmentary sectional view showing my punch machine.

FIGURE 3 is a sectional view taken on the line 33 of FIGURE 2.

FIGURE 4 is a sectional view taken on the line 44 of FIGURE 2.

FIGURE 5 is a sectional view of a modification of one of my electromagnets.

FIGURE 6 is a graph showing a curve of force versus gap of a simple, typical electromagnet.

FIGURES 2-4 show my invention embodied in a selective multiple gang punch machine 10, and FIGURES 1 and 1a are fragmentary schematic views showing the electromagnet-punch element relationship discussed before. Throughout the drawings, tolerances and clearances are greatly exaggerated.

Punch 10 (FIGURES 2-4) consists of a reciprocatory die 12 having a punch element guide 14 provided with guide holes aligned with the holes in the die. Die 12 and guide 14 are spaced apart to define a passage 16 for tape 18, and the die and guide are reciprocated in time with the code command signals of code source 20 (FIG- URE l). The code source 20 and reciprocatory driver 22 (shown as a linkage and motor-operated eccentric driver in FIGURE 2) are conventional.

In the gang punch configuration (FIGURES 2 and 3) I have a plurality of transverse rows 24, 24a 2411 of punch elements. Each row can have any number of punch elements depending on the kind of record (card, tape, five-channel tape, six-channel tape, etc.) for which the punch machine is designed. For instance (FIGURE 4), I have shown eight punch elements in row 2421 for an eight channel tape, but the number of punch elements in a row can obviously be increased or decreased.

Each punch element (see elements 25, 25a and 25b FIGURE 1) is constrained to straight-line motion by its disposition in a pair of aligned openings 30 and 32 in the reciprocatory guide 14 and a stationary guide 34,

respectively. Each punch element is adjustable to a punch position (not driven through the record) by its respective push wire 36, 36a, 36b, etc., attached to the armatures of electromagnets 38, 38a, etc. which respond to code command signals from source 20. It is preferred that the push wires be Bowden wires whose housings are attached to the frame of my machine. As shown in FIGURES 2 and 3 the punch elements must be in a tight cluster (for proper hole spacing in record 18), and the electromagnets occupy considerably more space. Thus, Bowden wires 36, 36a, etc. are curved arcuately outward to have one end in (or near) the cluster of punch elements and the other end attached to the armature of its respective electromagnet. The curvature of the wire is fixed, i.e. the wires are prebent to the desired shape so that they do not flex (they merely move endwise) in their operation.

As shown in FIGURE 1, the punch elements can be constructed integral with their respective push wires (see punch element 25 and its push wire 36). Alternatively, the punch elements can be made separate from their push wires as shown at 25b and 36b. In either case, the extent of longitudinal motion of the punch elements is limited by fixed stops 39 (attached to the frame of the machine) disposed in notches 40 in the sides of the punch elements.

The previously mentioned punch element guide 34 (FIGURES 1, 2 and 4) is a part of the frame of the punch machine. This frame also has wall 42 (FIGURE 2 only) attached by members 43 and 44 to guide 34. Of course, driver 22 is suitably attached to the machine frame, and the reciprocatory die 12 and guide 14 are constrained by conventional means (not shown) with respect to the machine frame.

Frame wall 42 has the magnetic cores of all of the electromtgnets 38, 38a, etc. fixed thereto, there being one electromagnet for each punch element and its push wire. As shown (FIGURE 2) the machine frame has intermediate guides 46 and 48 provided with apertures through which the housings of the Bowden push wires pass in extending from their respective electromagnets to their punch elements. The intermediate guides 46 and 48 constitute only one possible means to retain the smooth curvatures of the push wires (FIGURE 1). Other means can be used, such as tubes, spiral flexible guides held in suitable mountings and potting the entire assembly of push wire housings (after fixing the desired smooth curvatures) in a suitable plastic.

Operation In accordance with usual punch machine practice, code command signals are conducted to one or more of the electromagnets 38, 38a, etc. by means of conductors 50 (FIGURE 1) during the time that driver 22 is in a non-punching part of its reciprocatory cycle, i.e., as in FIGURE 1a. In the illustrated punch arrangement (with the die above the punch elements), the code signals are impressed on selected electromagnets just before or during the time that the die is at the top of its stroke (FIG- URE 1a) and during the time that the die lowers the tape 18 (FIGURE 1) an amount which is sufiicient for those punch elements under the command signals, to perforate the tape and enter the die holes. Then, the command signals may be discontinued and the die 12 and guide 14 (and the tape in passage 16) are lifted by driver 22. More is said of the general operation in the discussion (below) of my electromagnets whose arrangement forms an important feature of my punch machine.

Each electromagnet 38, 38a, etc. is of the variable air (flux) gap type, and is constructed to push its connected wire when actuated. More particularly (FIGURE 1), electromagnet 38 has a coil 60 on a pole piece 62 which is fixed to frame wall 42. Coil 60 is connected to one (or more) of the signal wires 50, and it is energized in response to a command code, or it is not energized 'in the absence of such a code. The armature 64 of the electromagnet has a gap surface 65 opposing the pole piece surface 68 of the electromagnet. One end of push wire 36 is attached to the armature by suitable means, e.g. set screw 70 and wire-length adjusting bolt 72 together with lock nut 74. An adjustable stop 78 fixed to frame wall 42 limits the downward motion of the armature and establishes the length of the air gap 80 when fully open. When a command signal is received by one of the electromagnets, e.g., for wire 36a in FIGURE 1a, the armature surface 65 of the associated electromagnet 38a (FIG- URE 1) is magnetically attracted toward surface 68 by the flux field across gap 80, thereby closing gap 80, and pushing wire 36a upward to push its punch element forward with respect to the non-commanded punch elements while the die 12 and guide 14 are in the elevating part of their cycle (FIGURE 1a). Thus, the punch element is actuated at no load, that is it does not punch the tape. Its electromagnet 38a merely moves the push rod and punch element to the forward position, and holds it in that position. Electromagnet 380 (FIGURE 5) simply shows a slightly different core and coil arrangement which is one of many possible variations.

As discussed before, the punch is held by the maximum force available from the electromagnet because the air gap 80 is closed and the axis of the push wire at armature 64 is perpendicular to the contacting surfaces 65 and 68 of the now-closed gap 80. During this maximum holding force application, driver 22 moves the die 12 downward (FIGURE 1) together with tape 18, causing all forward punch elements (36a in FIGURE 1) to perforate the tape and enter the die holes. For the reasons explained before, the force of the electromagnet is sufiicient to hold the punch element forward during tape (or card) perforation, but the same electromagnet will not provide a force sufiicient to drive the punch element through the tape (or card, not shown). In this regard, see Curve C in FIGURE 6, showing the plot of gap size versus force of a simple electromagnet. Note especially the sharp increase of force as the gap approaches zero.

After the punch portion of the cycle, the die begin-s to lift (like FIGURE 1a) and a tape (or card) feeder (not shown) moves the tape placing another portion in the throat (passage 16) of the machine. Bars 39 and notches 40 act as hold-back devices when the tape is stripped from the punch elements. There are four alternatives possible for punch element return. The raised punch elements and their Wires can be lowered by gravity, spring-returned, remain elevated due to the residual magnetic attraction across the deenergized electromagnet, or they can be deliberately held forward by the control current, if the same punch is to be used to perforate the medium during the next punch cycle. The last two alternatives are preferred for the following reason. Often a punch element is called upon to perforate the medium in successive cycles, and each time that this happens my magnetically retained punch elements will not be returned only to be again moved forward. As shown in FIGURE 1a there is ample clearance for tape-feeding with the punch elements forward. Also, if a punch remains forward by residual magnetism in the electromagnet and that element fails to receive a command signal for the next punch cycle, the shear strength of the tape is ample to break the residual hold and to return the punch element during that cycle.

It is understood that numerous modifications can be made. For example, my punch can be inverted or used on its side with approximately equal results. Instead of Bowden wires I can use rigid rods and/ or levers to couple the electromagnets to the punch elements. Also, the punches can be made to be the movable elements, while the dies can be made individually controllable, each die hole controlled by an electromagnet as a separate element. These and other variations within the scope of the claims can be resorted to.

I claim:

1. In a punch machine to form a record, a punch and die set, means to provide relative movement therebetween for a punch operation on the record, punch-programming electromagnets associated with the respective punches of said set, each electromagnet having a variable air gap wherein the attractive force thereacross is maximum when the gap is at a minimum, and means to energize selected electromagnets and complete the program-actuation at which the gaps of the associated electromagnets are minimum prior to a said punch operation so that at the time of said operation the selected punches are magnetically retained with maximum electromagnetic force owing to the closed condition of the gaps of the electromagnets associated with said selected punches.

2. The subject matter of claim 1 and means to constrain said punches to movement substantially normal to the record, and the punch reaction during punching of the medium being across said minimum gaps normal to the respective pairs of faces defining each gap.

3. The subject matter of claim 1 wherein residual magnetism of the electromagnets of the programmed punches retain the programmed punches in the programmed position to so remain if the same said punches are required to perforate the record in the subsequent punch operation.

4. The subject matter of claim 1 wherein said punch and die set includes a die plate and a connected punch guide having holes for the punches aligned with the die holes, said die plate and guide being spaced to provide a record passage, and said relative movement providing means including a driver to reciprocate said die plate and guide.

5. In a punch machine having a punch and die set, a plurality of electromagnets operatively connected with the punch elements of said set, each electromagnet having an armature and a pole piece with a variable air gap therebetween, means to energize selected electromagnets and for thereby programming the machine by moving the associated punch elements and at the same time closing the gaps of the energized electromagnets for maximum attraction thereacross, and means to thereafter provide relative movement between the punch elements and die of the set for perforating a record while said associated punch elements are electromagnetically held fixed relative to their electromagnets.

6. The punch machine of claim 7 wherein said relative movement providing means include a reciprocatory driver, said die being driven by said driver, and means operatively associated with said die for reciprocating the record therewith.

7. The punch machine of claim 8 wherein said record reciprocating means include a guide adjacent to said die, and said guide having apertures which form guides for said punch elements.

8. In a punch machine, a punch and die set including a die plate and a plurality of punch elements, electromagnetic means to move forward selected punch elements and retain said selected elements in the forward position during a record-perforating operation, said electromagnetic means for each punch element including an electromagnet having a pole piece and an armature defining a variable air gap, means for energizing the electromagnet prior to record-perforation at a time sufficient for the armature to move against the pole piece thereby closing said gap and developing maximum tractive force across the closed gap, and means then operative to provide relative movement between said die plate and all of said punch elements axially of said elements to cause those punch elements whose electromagnets are energized to perforate the medium.

9. The punch machine of claim 8 wherein each of said punch elements has a push wire associated therewith, and means for connecting said push wires to said electromagnet armatures.

10. The punch machine of claim 9 wherein said push wire connecting means include an effective-length adjusting means for said wires.

11. For use with a paper medium adapted to be impacted, a plurality of members, means constraining said members to axial motion substantially normal to the surface of the medium, an electromagnet operatively associated with each member, each electromagnet including a coil and pair of pole pieces one of which is movable relative to the other to define a variable air gap, the electromagnetic attraction between said pole pieces being maximum when said gap is substantially zero and said coil is energized to retain said pole pieces together, said movable pole piece being operatively associated with one of said members, and means operative while said gap is substantially zero and said pole pieces are held together by energization of said coil for effecting impact of said paper medium by the member whose electromagnet pole pieces are retained with substantially zero gap so that the maximum electromagnet attraction therebetween is utilized at the instant of said impact.

12. For use with a paper medium adapted to be impacted, a plurality of elongate movable members, means for constraining the movement of said members to axial motion substantially normal to the paper medium at the instant of impact, an electromagnet actuator for each member, each actuator including a fixed part, a movable part, and a coil, said movable part being movable between a first position distal from said fixed part and a second position in substantially contacting relation to said movable part, the spacing between confronting surfaces of said parts defining a flux gap which becomes flux-energized upon excitation of said coil in a manner such as to attract said surfaces so that maximum tractive force between said parts occurs when said gap is reduced to substantially zero, said member being arranged for movement with said movable part so that said actuator exerts maximum holding force for said member when said gap is substantially zero, and means operative while said gap is substantially zero for effecting impact of the paper medium with said member.

13. The subject matter of claim 12 and means for selectively adjusting the stroke of said member.

14. For use with a flexible medium having a surface adapted to be impacted, a plurality of elongate members, means for constraining the movement of said members to axial motion substantially normal to the surface of said medium at the instant of impact, electromagnetic means for programming selected members prior to impact with said medium, said electromagnetic means for a said member including an excitation coil, and a fixed pole piece and a relatively movable pole piece, said pole pieces having confronting faces forming a variable flux gap, the magnetic coupling between said pole pieces being greatest when said coil is excited by a programming signal and said movable pole piece has thereby moved to a position such that said flux gap is substantially zero, and other means operable after selected members have been programmed by their associated electromagnetic means, for effecting impact of the medium by said selected members.

References Cited by the Examiner UNITED STATES PATENTS 3,019,966 2/62 Scribner 234108 X 3,143,288 8/64 Biegel 234131 X FOREIGN PATENTS 1,239,352 7/60 France.

ANDREW R. JUHASZ, Primary Examiner.

WILLIAM S. LAWSON, Examiner. 

1. IN A PUNCH MACHINE TO FORM A RECORD, A PUNCH AND DIE SET, MEANS TO PROVIDE RELATIVE MOVEMENT THEREBETWEEN FOR A PUNCH OPERATION ON THE RECORD, PUNCH-PROGRAMMING ELECTROMAGNETS ASSOCIATED WITH THE RESPECTIVE PUNCHES OF SAID SET, EACH ELECTROMAGNET HAVING A VARIABLE AIR GAP WHEREIN THE ATTRACTIVE FORCE THEREACROSS IS MAXIMUM WHEN THE GAP IS AT A MINIMUM, AND MEANS TO ENERGIZE SELECTED ELECTROMAGNETS AND COMPLETE THE PROGRAM-ACTUATION AT WHICH THE GAPS OF THE ASSOCIATED ELECTROMAGNETS ARE 